Tibial Guides, Tools, and Techniques for Resecting the Tibial Plateau

ABSTRACT

Various patient-specific tibial guide housings, patient-specific tibial guide boxes, and methods of resecting the tibial plateau are disclosed herein.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/865,958, entitled “Tibial Guides, Tools, and Techniques for Resectingthe Tibial Plateau” and filed Apr. 18, 2013, which in turn claims thebenefit of U.S. Provisional Application Ser. No. 61/635,270, entitled“Tibial Guides, Tools, and Techniques for Resecting the Tibial Plateau”and filed Apr. 18, 2012, the disclosure of each which is incorporatedherein by reference in its entirety.

TECHNICAL FIELD

This disclosure relates to improved and/or patient-adapted (e.g.,patient-specific and/or patient-engineered) surgical guides, tools andtechniques to assist with the resection of the tibial plateau or similarbones. More specifically, the present disclosure provides a set ofalignment and cutting guides and methods for use that are easier andmore reliable for use by experienced and inexperienced knee surgeons.

BACKGROUND

When a patient's knee is severely damaged, such as by osteoarthritis,rheumatoid arthritis, or post-traumatic arthritis, it may be desirous torepair and/or replace portions or the entirety of the knee with a totalor partial knee replacement implant. Knee replacement surgery is awell-tolerated and highly successful procedure that can help relievepain and restore function in injured and/or severely diseased kneejoints.

In a typical knee surgery, the surgeon will begin by making an incisionthrough the various skin, fascia, and muscle layers to expose the kneejoint and laterally dislocate the patella. The anterior cruciateligament may be excised and/or the surgeon may choose to leave theposterior cruciate ligampnt intact—such soft tissue removal oftendepends on the surgeon's preference and condition(s) of the ACL/PCL.Various surgical techniques are used to remove the arthritic jointsurfaces, and the tibia and femur are prepared and/or resected to acceptthe component artificial implants.

Preparing the surface of the tibia often requires that the surgeonresect the articular surface of the bone to receive an implant over theresected surface. The resection can include specific depths of cut(s),posterior slope(s), varus/valgus angle(s), and/or axial alignment(s)that can be unique to every patient. The specific dimensions and/ormeasurements desirably ensure proper positioning of the artificial jointcomponent assembly, and accurate guiding and cutting of the tibialplateau is important to achieve the most accurate and best fit of theartificial implant components.

Traditionally, a surgeon has two options to help them prepare the tibia.The surgeon may select the traditional “freehand” method, or he/she maychoose a set of surgical instruments that will assist with positioning,resection and alignment. The “freehand” method usually involves standardsurgical tools available in the operating room (OR) during surgery, suchas osteotomy drills and calipers for measuring. The procedure,preparation, alignment and/or resection may be more or less accurate,depending on the level of the skill and/or ability of the surgeon. Wheresurgical guide tools are chosen, the surgeon may employ a standard sizedsaw guide block or other resection guides, which desirably assist withthe critical cuts required in the tibial plateau. A saw guide block orresection guide can first be attached to the patient in various ways,and then an alignment device can be used to provide a desired alignment.Once the resection guide is aligned, it can be temporarily fixed inplace on the anterior side of the tibia, and the alignment deviceremoved to allow the cutting or resection operation. While the use ofsuch standard sized guide blocks or resection guides can improve thesurgical procedure, they may not provide sufficient fine adjustments forcutting depth and/or slope, may be bulky, and may not be easy to use.The misuse or non-use of such devices can result in improper depth ofcut, improper posterior slope, malalignment of varus/valgus angle(s),and poor axial alignment that may contribute to poor artificial implantpositioning, instability of the joint, and poor surgical outcomes.

As a result, it has been recognized that it would be desirable toprovide a more effective system of guides, tools, instruments andmethods to facilitate a high degree of success in the preparation of thetibial plateau to receive an artificial joint.

SUMMARY

Some disclosed embodiments include a tibial guide housing for use intreatment of a tibia. The tibial guide housing can include a firstreference arm with a patient-specific contact surface configured toconform to a first portion of the superior surface of the tibia. Thetibial guide housing can also include a second reference arm having apatient-specific contact surface configured to conform to a secondportion of the superior surface of the tibia. Additionally, the tibialguide housing can include at least one pin hole configured toaccommodate insertion of a pin through the tibial guide housing and intothe tibia. The tibial guide housing can also include a patient-specificcontact surface configured to conform to a portion of an anteriorsurface of the tibia.

Some embodiments can include a system for preparing a tibial plateau.The system can include a tibial guide housing and one or more tibialcutting guide boxes, each of the one or more tibial cutting guide boxes.The tibial cutting guide boxes can include a patient-specific contactsurface configured to conform to a portion of the anterior surface ofthe tibia. The tibial cutting guide boxes can also include a guideaperture configured to accommodate a surgical cutting tool and guide thecutting tool along a cutting plane having a predetermined cut depth andangle. Additionally, the tibial cutting guide boxes can include at leastone pin hole configured to accommodate a pin passing into the tibia.

These and other objects, advantages, and features of the disclosure willbe apparent from the following description, considered along with theaccompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 depicts a top plan view of one embodiment of a tibial guidehousing and/or body;

FIG. 2 depicts a bottom plan view of the tibial guide housing of FIG. 1;

FIG. 3 depicts a front view of the tibial guide housing of FIG. 1;

FIG. 4 depicts a back view of the tibial guide housing of FIG. 1;

FIG. 5 depicts a right-side view of the tibial guide housing of FIG. 1;

FIG. 6 depicts a left-side view of the tibial guide housing of FIG. 1;

FIG. 7 depicts an isometric perspective view of the tibial guide housingof FIG. 1;

FIGS. 8A-8C depict isometric perspective views of different embodimentsof tibial guide boxes having various cut depths constructed inaccordance with the teaching of the present invention;

FIG. 9 depicts a bottom plan view of a tibial guide box;

FIG. 10 depicts a top plan view of a tibial guide box;

FIG. 11 depicts a front view of a “minus two cut depth” tibial guidebox;

FIGS. 12A-12C depicts various views of a knee joint at neutral, varusand valgus angles, depicting possible posterior slopes of the knee;

FIGS. 13A and 13B generally depict various examples varus and valgusguide cut slots that can be designed as standard and/or adjustablefeatures, for adjusting varus/valgus angles;

FIG. 14 depicts a back view of a “zero cut depth” guide box;

FIG. 15 depicts a side view of the guide box of FIG. 14;

FIGS. 16A-16C depict isometric perspective, front plan, and back viewsof one embodiment of an assembled tibial guide assembly;

FIGS. 17A & 17B depict a top plan view and an anterior view of apatient's tibia remodeled by a computer system;

FIG. 18 depicts an anterior view of a tibial guide housing positioned ona medial side of a tibia;

FIG. 19 depicts an anterior view of the tibial guide assembly and tibiaof FIG. 18, with a “zero” tibial guide box inserted into the tibialguide housing;

FIG. 20 depicts a top plan view of a tibial guide assembly, withexemplary medial and lateral cut planes;

FIG. 21 depicts a posterior view of a tibial guide assembly positionedon a medial side of a tibia;

FIG. 22 depicts a side view of a tibial guide assembly, with both medialand lateral sides of a tibia resected;

FIG. 23 depicts a posterior view of the tibial guide assembly with anoptional cut plane;

FIG. 24 depicts an exemplary knee joint with tibial cuts planned todiffering levels and depths;

FIG. 25 depicts the knee joint of FIG. 24 in which a medial tibialsection has been resected using a substantially horizontal cut and alateral tibial section has been resected at a relatively steep angle;

FIG. 26 depicts the tibia of FIG. 25, wherein a substantially thickerlateral insert than medial insert has been employed to create a desiredresulting angulation;

FIG. 27 illustrates a coronal plane of the knee with exemplary resectioncuts that can be used to correct lower limb alignment in a kneereplacement;

FIG. 28 depicts a coronal plane of a knee shown with femoral implantmedial and lateral condyles having different thicknesses to help tocorrect limb alignment; and

FIG. 29 illustrates a virtual model of a patient's limb that ismisaligned in the sagittal plane, and a virtually corrected limb.

DETAILED DESCRIPTION

The present disclosure provides an improved patient-specific orpatient-engineered tibial resection guide alignment apparatus(hereinafter “resection guide”) and associated methods that desirablyovercome and/or address various disadvantages of existing systems, aswell as provide for controlled depth and/or slope cuts on the tibia.Various embodiments of the present disclosure may be used to facilitatetotal knee surgery, bicompartmental knee surgery or unicompartmentalknee surgery. In addition, the various embodiments can be used forcruciate retaining surgeries or non-cruciate retaining surgeries.

Various embodiments of the present disclosure may be patient-specific orpatient engineered for each surgical patient, with each tibial resectionguide alignment apparatus tailored to an individual patient's jointmorphology. In at least one preferred embodiment, the system may bedesigned as an assembly that comprises a patient specific tibialresection housing and/or body and several patient specific sized cuttingblocks that can be inserted into the housing/body and used for resectingthe tibial plateau.

In various embodiments, each piece of the tibial resection guideassembly can be uniquely tailored to an individual patient's anatomy,which may require images taken from the subject. The manufacturer canthen design the patient-specific resection guide using the joint imagefrom a patient or subject, wherein the image may include both normalcartilage and diseased cartilage; reconstructing dimensions of thediseased cartilage surface to correspond to normal cartilage (using, forexample, a computer system) and/or bones; and designing the tibialresection guide to exactly or substantially match the dimensions of thediseased cartilage surface, the normal cartilage surface, a healthycartilage surface, a subchondral bone surface, and/or variouscombinations thereof (including height, width, length, and/or referencepoints of the resection guide). In various alternative embodiments, theguide may substantially match an area slightly greater than the diseasedcartilage surface or bone surface (or any other known size that may beapplied to any patient).

The image can be, for example, an intraoperative image including asurface and/or feature detection method using any techniques known inthe art, e.g., mechanical, optical, ultrasound, and known devices suchas MRI, CT, ultrasound, and other image techniques known in the art. Incertain embodiments, reconstruction is performed by obtaining a surfacethat follows the contour of the normal cartilage or the natural anatomyof the bone. The surface can be parametric and include control pointsthat extend the contour of the normal cartilage to the diseasedcartilage and/or a B-spline surface to determine the shape of at leastone contact surface of the tibial resection guide to fill the areas ofdiseased cartilage. The images can be 2D or 3D or combination thereof tospecifically design the tibial resection guide assembly.

In various embodiments, tibial resection guide assemblies constructed inaccordance with various teachings described herein may be designed asextramedullary or intramedullary. Exemplary extramedullary guides ortools can be connected outside the patient's tibia, and may be designedto include an attachment for alignment rods or any other alignmentmechanisms. Exemplary intramedullary alignment guides or tools caninclude an intramedullary rod that positioned into the central canal ofthe tibia with the alignment mechanism suspended from the rod.

Various embodiments can include a patient specific housing and/or bodydesigned to include various reference points that correspond to apatient specific articular contact surface and/or subchondral bonesurface (or other surface, as desired). These reference points may beperpendicular extensions or “fingers” that extend from the body toprovide tibial surface anchoring. These reference points may include atleast one extension, finger or arm that incorporates at least onepatient specific contact surface on the articular or other surface ofthe tibia. The reference points may be designed to have varied lengthsonto the surface of the tibia, or may be shortened to the minimumanchoring required. The reference points may be designed centrallylocated or can be offset to varying degrees to provide an optimalnatural conforming location on the articular or other surface of thetibia to allow for stable resection.

The tibial resection guide assembly can further include one or moreguide boxes that may be removably attached to the surface. The boxes maybe designed to include various patient specific contact surfaces toeasily mate with the anterior surface of the bone. The boxes may have atleast one guide aperture for guiding a surgical cutting instrument forcontrolled resection of the tibia plateau. The guide boxes may also bedesigned to make cuts that are parallel, non-parallel, perpendicular, ornon-perpendicular to other cuts.

The tibial guide boxes can be designed as removable or permanent. If thetibial guide boxes are removable, they may have a sliding mechanism thatallows for easy insertion into the tibial guide resection housing and/orbody. They may include other connection arrangements, including railsystems, quick connects, or other similar mechanisms for insertion intoand/or connection to the guide resection housing and/or body.

Various aspects of the disclosed embodiments may be used and/or appliedto a variety of other joints, such as the shoulder, hip, and wrist.

Tibial Guide Assembly Apparatus

Described herein are various embodiments of surgical tools and methodsfor accurately preparing the medial and lateral tibial plateau such thatthe plane of each cut across the bone ends will be appropriate toreceive the portions of a knee prosthesis selected to reflect thespacing distance and size of the respective bone ends, so that one ormore artificial knee joint components will properly and optimallyreplace the mechanical functioning of a normal knee.

In various embodiments, the tibial plateau preparation assembly caninclude: a tibial guide housing, one or more tibial cutting guide boxeswith a cutting platform with a tibial depth resection guide, andoptional attachment of an alignment rod. In practice, a surgeon, afteropening and/or accessing the damaged knee area, may use the tibial guideassembly to prepare medial and lateral ends of a patient's tibia toreceive appropriate knee components, such as a tibial tray and insert.

FIG. 1 depicts a top view of a tibial guide housing and/or body 25. Thetibial housing is equipped with a variety of features that will assistthe surgeon in his preparation of the tibial plateau; it is designedwith a viewing window 20, an alignment indicator 10, an angled lowprofile body 30 and 40 and ergonomic features 50 and 60. First, thetibial guide housing contains a viewing window 20 to assist the surgeonin placement on the anterior surface of the tibia. This window willallow the surgeon to view the peripheral edge of the anterior surface ofthe tibia. The window, as depicted in FIG. 1, is designed substantiallysimilar to the width of the tibial guide housing because it maximizesviewing capacity, but may be designed to have a smaller width or alarger height to accommodate the surgeon's need. The dimensions of thiswindow may be designed as standard sizes or shapes or may bepatient-specific to accommodate the tibial anatomy. The window may be avariety of shapes such as “Z,” or curved shaped, or “L” shaped.

A second feature is the alignment indicator 10. This indicator providesthe surgeon with visual assistance that the housing is firmly planted onthe anterior surface of the tibia. The present tibial guide housing hasthe alignment indicator 10 designed as a small channel. However, themanufacturer may choose to design this indicator on the surface of thehousing with additional visual indicators such as an arrow. Thealignment indicator may be any size, shape or dimension. The alignmentindicator may also be designed as patient specific to match orsubstantially match the perimeter of the tibia.

The tibial guide housing may be designed to have a low profile forsurgery. A design that is low profile has many advantages because thereis often minimal space available above and/or adjacent to the tibiaduring cruciate ligament retaining procedures. The angled front 30 ofthe tibial guide housing achieves this purpose. Also, the width 40 ofthe housing is also smaller than other available cutting guides. Thewidth of the housing 40 minimizes the profile of the cutting guide andmay be designed as patient specific.

The tibial guide housing may be designed to have ergonomic features,such as the extension tab 50 and radiused edges 60. The extension tab 50allows the surgeon to grasp and handle the tibial guide housing by itsedge. The edges within the extension tab are radiused 60 to provide foreasy finger transition and no sharp edges. The width of this extensionmay be designed with varying heights or shapes. The manufacturer maydesign this with a “U” shape or other variety of shapes to accommodateholding of the housing.

FIG. 2 depicts a bottom view of the tibial guide housing, showing thereference arms 90, and the patient-specific contact surfaces 70 and 120.The tibial guide housing may be designed with specific referenceextensions/arms 90 to help the surgeon find the natural, conformingposition for more accurate resection. If the surgeon is resecting themedial side of the tibial plateau, the surgeon will place the referencearms 90 on the articular surface of the tibia and move it around untilthe reference arms finds their own natural, conforming position(s). Thereference arms may be designed with at least one reference arm, but invarious preferred embodiments can include three reference arms. Thereference arms may respectively be titled as the “medial reference arm,”which may align with the center of the medial tibial plateau, the“center reference arm,” which can align between the tibial spines, andthe “left reference arm,” which can align with the center of the tibia.Each reference arm can be made patient specific or be made with standardavailable sizes retrieved from a database. The reference arms spacing 80may vary with every patient, or a set spacing may be designed orincorporated between each reference arm. In addition, the medialreference arm and the center reference arm may also havepatient-specific angles 100 designed into the housing, or angles 100 maybe set standard angles derived from a database. The length 110 of eachreference arm may also vary between each patient (i.e., be apatient-specific length). In various embodiments, the tibial guidehousing surfaces 120 and 70 that contact the anterior portions of thetibia will be patient specific to provide a secure and conforming fit.

FIG. 3 depicts a front view of the tibial guide housing. The front viewhighlights specific features such as the dovetail rail 130, thealignment rod attachment 170, the low profile width 160 and height 150for tibial guide box insertion, and the tibial guide box positive stops140. The dovetail rail 130 is designed within the tibial guide housingto allow and/or facilitate easy insertion and securement of the tibialguide boxes (see FIG. 8A-8C). This also allows locking of the tray intothe housing and prevents any unnecessary motion or movement duringcutting. The tibial guide boxes may be secured into the tibial guidehousing using any mechanism that is known in the art. If desired, thetibial guide boxes may be secured by inserting the boxes into thehousing and securing by set screws, by press fit, by snap tabs, or otherequivalent mechanisms. Alternatively, the bottom may be designed with arecessed tray that seats the tibial guide box.

The tibial guide housing height 150 and width 160 may be designedspecifically to fit one or more of the tibial guide cutting boxes. Thedimensions may be minimized to provide a low profile for the assembly,or they may have different shapes to facilitate insertion of the guideboxes. The dimensions may also be patient-specific. The height 150and/or width 160 may vary depending on the morphology or other featuresof the damaged or diseased tibia and articular surfaces. The tibialguide housing may also provide positive stop walls 140 to prevent thetibial guide boxes from sliding forward or other directions as well asto potentially prevent the surgeon from over-exerting pressure duringinsertion. The surgeon can insert the guide box into the guide housinguntil it reaches a detent or stop to provide accurate alignment. Thetibial guide housing may also include an alignment leg 170 to allowattachment of the tibial alignment rod to the body.

FIG. 4 depicts a back view of the tibial guide housing and highlightsthe patient contact surfaces 190 and the curved exterior wall 180. Thecontact surfaces 190 may be patient specific. The image data evaluatedto manufacture the housing can be used to design the surface thatcontacts or mates with the articular surface of the tibial plateau, thushaving or approximating a patient specific shape(s). Such features canallow stability and more secure attachment when resecting or cutting istaking place. The exterior wall can be radiused 180, as desired, toeliminate, reduce or minimize soft tissue irritation.

FIG. 5 depicts a right-side view of the tibial guide housing and/orbody. In this view, various detent receiver holes 230 are shown. Thesedetent receiver holes 230 can receive a tibial guide insert box, and invarious embodiments the successful insertion can be accompanied by anaudible sound or other indication to the surgeon when the box is securedin place. The detent receiver holes 230 can be designed as a receiverfor tabs, levers, etc., or they may have different shapes. The alignmentleg angle 200 and the alignment leg 220 are also shown in this view. Theangle and the length of the alignment leg may be designed as patientspecific for increased accuracy in the alignment of the housing to thecenter axis of the tibia. The alignment leg angle 200 and the height 220may also be designed as standard dimensions that can be determined fromevaluations from a database of various patients. The alignment leg mayalso be designed to include various connection types, including pressfit insertion. For easy removal, the alignment leg may include a quickrelease/connection mechanism for the surgeon's use that can preventexcessive upward force on the tibial guide housing. This side view alsohighlights an example of the patient specific nature of the contactsurfaces 190 of the tibial guide housing.

FIG. 6 depicts a left-side view of the tibial guide housing and/or body.This view highlights the relative thickness/height 240 of a referencearm, as well as an exemplary pin hole 250. The reference armthickness/height 240 may be designed as patient specific. Each referencearm may have different thicknesses/heights to accommodate the diseasedpatient's surface. The thickness/height of each arm may also be designedto have standard dimensions as derived from a database of similarpatients. The tibial guide housing may have one or more pin holes 250 tohelp secure the housing to the tibia. The pin holes may be designedlarge enough to accommodate a drill and to insert pins for visualguidance or location on the tibia.

FIGS. 8A-8C depict isometric perspective views of various embodiments ofdifferent tibial guide boxes that can be used with various featuresdisclosed herein, with various available cut depths included in onepreferred embodiment. FIG. 8A shows the “+2” tibial guide box that canbe employed by the surgeon to make a primary cut to the tibia. This box,along with other system features, desirably facilitates the surgeon'sability to adjust the resection or cut of the tibial plateau after aprimary cut has been completed. In the embodiment shown in FIG. 8B, theprimary cut can be defined as the “0” tibial guide box. In variousprocedures, the “0” guide box will be inserted and utilized by thesurgeon to make the primary cut and may be, in various embodiments, apatient-specific selected or derived depth. FIG. 8C shows a “−2” guidebox which can also allow the surgeon to adjust the cut after the primarycut has been made. Many other cut depths can be created to allow thesurgeon to make additional controlled depth cuts on the tibial plateau.

FIGS. 9 and 10 depict the bottom and top plan views, respectively, of atibial guide box. In these embodiments, the bottom view of the guide boxshows a dovetail rail 260, and the positive stop tabs 270. The dovetailrail 260 may have varying widths or lengths for quick and guidedinsertion of the tibial guide boxes. The positive stop tabs 270 aredesigned to extend to contact the positive stop walls 140. FIG. 10 showsthat the cut guide cover 300 need not necessarily extend the full depthof the tibial guide box. However, the cut guide cover may be designed toreach the entire length/depth of the tibial guide box. In addition, thecut guide cover may be manufactured out of variety of materials thatwould withstand an oscillating or reciprocating saw. It can bemanufactured out of biocompatible metals and/or plastics.

FIG. 11 depicts a front view of a minus two cut depth guide box. Thisspecific guide cut box need not necessarily have a cut guide cover 300because it can use the roof of the tibial guide housing as a portion ofthe cut guide cover. In contrast, FIGS. 8A and 88B depict guide cutcovers 300 that are designed in portions of the boxes. FIG. 11 furtherdepicts two pin holes 320 that may be incorporated into the design ofeach tibial guide cut box. The tibial guide box may have pin holes 320to help secure the box to the tibia. The pin holes may be designed largeenough to accommodate a drill and to insert pins for visual guidance orlocation on the tibia. Also, additional pin holes may be designed intothe guide box or guide housing. As previously noted, the “−2” guide boxstill can guide 310 the reciprocating saw or the oscillating saw byusing the roof the tibial guide housing as a guide boundary. This guidedslot 310 may be manufactured to specific dimensions to accommodatestandard oscillating or reciprocating bone saws. In another embodiment,the guided slot 310 may also incorporate various angles, shaped and/orconfigurations, including different features to accommodate differentvarus/valgus (see FIG. 13) and/or anterior/posterior angles (see FIG.12C) designed within the box.

FIGS. 12A and 12B depict a human knee with exemplary varus, neutral andvalgus orientations, and various exemplary angles that a cut guided slot30 or other tool may incorporate to accommodate and/or correct suchorientations. In a varus knee, this line passes medial to the knee and amoment arm is created, which increases force across the medialcompartment of the knee. In a valgus knee, the load-bearing axis (LBA)passes lateral to the knee, and the resulting moment arm increases forceacross the lateral compartment of the knee. In various embodiments,specifically designed tibial guide boxes that incorporate patientspecific varus/valgus angles could be employed to reduce and/or correctsuch deformities, desirably reducing abnormal forces in the artificialknee joint, and returning the LBA to a normal functioning knee at itsneutral position. FIG. 13A depicts various cut guide slot angulationsthat, when used in conjunction with a tibial guide box as describedherein, can generally be employed to alter the resulting varus or valgusangles of one or more tibial cut planes. FIG. 13B depicts onealternative embodiment of a guide tool that incorporates an adjustmentmechanism 322 that can be employed and adjusted to alter the cut angle.The adjustment mechanism could include a screw thread or other mechanismthat allows a wide variation in the cut plane angle, which could includelarger wedges to accommodate more severe varus/valgus angles. In variousembodiment, the guide tool with the adjustable mechanism could be sizedand configured to fit into the standard guided slots 1301-1304 as shownin FIG. 13A.

In at least one alternative embodiment, various features of guide toolsand surgical methods described herein can be used in conjunction with awide variety of tibial trays, wedges and/or tibial inserts toaccommodate the correction and/or reduction of extremely high varusand/or valgus angles in a given patient's anatomy. In such embodiments,a surgeon may choose to resect the medial and lateral portions of thetibia to differing levels and/or depths, as shown in FIG. 24, in which amedial tibial section has been resected using a substantially horizontalcut 2401, and a lateral tibial section has been resected at a relativelysteep angle, desirably removing a minimal amount of bone from thelateral side (see FIG. 25). After resection and creation of therespective tibial cut planes, the surgeon can choose to employ variouscombinations of tibial trays (e.g., separate medial and lateral trays)and/or inserts (e.g., dual inserts) to desirably create and/or replicatemedial and lateral tibial condylar surfaces that improve and/or correctthe varus and/or valgus angles of one or both of the patient's kneejoints. In the embodiment shown in FIG. 26, a substantially thickerlateral insert 2601 (as compared to the thickness of the medial insert2602) has been employed to create a desired resulting angulation for theknee implant. In one alternative embodiment, a single tibial tray may beused with a single or multiple tibial cuts, with a one or two pieceinsert having differing thickness on each of the medial/lateral portionsin a similar manner.

In addition, valgus deformities may lead to patients with deformed orhypoplastic lateral condyles. In fact, hypoplastic lateral condyles maybe present in 20% of patients that require knee replacement. An implantor tibial guide assemblies or other tools may be engineered frompatient-specific data to address this deformity, by correcting oroptimizing the lateral condyle, can include one or more expandedcurvatures in one or more locations on the lateral condyle, relative tothe patient's corresponding uncut medial or lateral condyle. Forexample, an implant may be engineered to include additional material onthe outer, joint-facing surface of the implant component's lateralcondyle. The expanded curvature(s) and/or material on the outside of thecondyle can be used to design a material savings on the inside of thecorresponding section of the implant component, for example, bymaintaining a minimum material/implant thickness from the outside(joint-facing surface) to the inside (bone-facing surface) of theimplant component. In this way, by adding material to the externalcontour of the implant component and maintaining a minimum materialthickness of the implant component, bone preservation can be maximized.Specifically, with more material on the joint-facing surface of theimplant and less material on the inner, bone-facing surface of theimplant, the resection cuts are made closer to the surface of the bone.Accordingly, this approach uses the patient-adapted design of theimplant component to both correct a condyle shape abnormality, such as alateral condyle abnormality, such as hypoplasia, and to maximize bonepreservation. In another embodiment, the deformity may be corrected bytailoring the tibial resection guide assemblies to have a unique medialand lateral assembly that will correct the angles. For example, thelateral condyle tibial resection guide may require smaller/lesserresection depth cut, different varus/valgus angle, or posterior/anteriorangle than the medial tibial resection guide. Other tools and methodsmay be similarly designed to correct the deformity.

In an alternative embodiment, the tibial guide assembly, the jointimplants, and other tools may be preoperatively designed and/or selectedto correct the misalignment and/or obtain a proper mechanical alignmentof a patient's limb. For example, based on the difference between thepatient's misalignment and the proper mechanical axis, a knee implantand implant procedure can be designed and/or selected preoperatively toinclude implant and/or resection dimensions that substantially realignthe patient's limb to correct or improve a patient's alignmentdeformity. In addition, the process can include selecting and/ordesigning one or more surgical tools (e.g., guide tools or cutting jigs)to direct the clinician in resectioning the patient's bone in accordancewith the preoperatively designed and/or selected resection dimensions.

In certain embodiments, the degree of deformity correction that isnecessary to establish a desired limb alignment is calculated based oninformation from the alignment of a virtual model of a patient's limb.The virtual model can be generated from patient-specific data, such 2Dand/or 3D imaging data of the patient's limb. The deformity correctioncan correct varus or valgus alignment or antecurvatum or recurvatumalignment. In a preferred embodiment, the desired deformity correctionreturns the leg to normal alignment, for example, a zero degreebiomechanical axis in the coronal plane and absence of genu antecurvatumand recurvatum in the sagittal plane.

The preoperatively designed and/or selected implant or implantcomponent, resection dimension(s), and/or cutting guides, templates orcutting jig(s) can be employed to correct a patient's alignmentdeformity in a single plane, for example, in the coronal plane or in thesagittal plane, in multiple planes, for example, in the coronal andsagittal planes, and/or in three dimensions. For example, where avirtual model of a patient's misaligned lower limb is used to virtuallycorrect the limb, a deformity correction can be achieved by designingand/or selecting one or more of a resection dimension, an implantcomponent thickness, and an implant component surface curvature thatadjusts the mechanical axis or axes into alignment in one or moreplanes. In various embodiments, a lower limb misalignment can becorrected in a knee replacement by designing or selecting one or more ofa femoral resection dimension, a femoral implant component thickness, afemoral implant component surface curvature, a tibial resectiondimension, a tibial implant component thickness, a tibial implantcomponent insert thickness, and a tibial implant component surfacecurvature (or various combinations thereof) to adjust the femoralmechanical axis and tibial mechanical axis into alignment in the coronalplane.

FIG. 27 illustrates a coronal plane of the knee with exemplary resectioncuts that can be used to correct lower limb alignment in a kneereplacement. As shown in the figure, the selected and/or designedresection cuts can include different cuts on different portions of apatient's biological structure. For example, resection cut facets onmedial and lateral femoral condyles can be non-coplanar and parallel1602, 1602′, angled 1604, 1604′, or non-coplanar and non-parallel, forexample, cuts 1602 and 1604′ or cuts 1602′ and 1604. Similar, resectioncut facets on medial and lateral portions of the tibia can benon-coplanar and parallel 1606, 1606′, angled and parallel 1608, 1608′,or non-coplanar and non-parallel, for example, cuts 1606 and 1608′ orcuts 1606′ and 1608. Non-coplanar facets of resection cuts can include astep-cut 1610 to connect the non-coplanar resection facet surfaces.Selected and/or designed resection dimensions can be achieved using oneor more selected and/or designed guide tools (e.g., cutting jigs) thatguide resectioning (e.g., guide cutting tools) of the patient'sbiological structure to yield the predetermined resection surfacedimensions (e.g., resection surface(s), angles, and/or orientation(s)).In certain embodiments, the bone-facing surfaces of the implantcomponents can be designed to include one or more features (e.g., bonecut surface areas, perimeters, angles, and/or orientations) thatsubstantially match one or more of the resection cut or cut facets thatwere predetermined to enhance the patient's alignment. As shown in FIG.27, certain combinations of resection cuts can aid in bringing thefemoral mechanical axis 1612 and tibial mechanical axis 1614 intoalignment 1616.

Alternatively, or in addition, certain implant features, such asdifferent implant thicknesses and/or surface curvatures across twodifferent sides of the plane in which the mechanical axes 1612, 1614 aremisaligned also can aid correcting limb alignment. For example, FIG. 28depicts a coronal plane of the knee shown with femoral implant medialand lateral condyles 1702, 1702′ having different thicknesses to help tocorrect limb alignment. These features can be used in combination withany of the resection cut 1704, 1704′ described above and/or incombination with different thicknesses on the corresponding portions ofthe tibial component. As described more fully below, independent tibialimplant components and/or independent tibial inserts on medial andlateral sides of the tibial implant component can be used enhancealignment at a patient's knee joint. An implant component can includeconstant yet different thicknesses in two or more portions of theimplant (e.g., a constant medial condyle thickness different from aconstant lateral condyle thickness), a gradually increasing thicknessacross the implant or a portion of the implant, or a combination ofconstant and gradually increasing thicknesses.

FIG. 29 illustrates a virtual model of a patient's limb that ismisaligned in the sagittal plane, for example, a genu antecurvatumdeformity, and the virtually corrected limb. The deformity correctioncan be achieved using a similar design approach as described above for acoronal plane deformity. However, the selection and/or design of one ormore femoral resection dimensions, femoral implant componentthicknesses, femoral implant component surface curvatures, tibialresection dimensions, tibial implant component thicknesses, tibialimplant component insert thicknesses, and/or tibial implant componentsurface curvatures can be used to adjust the femoral mechanical axis andtibial mechanical axis into alignment in the sagittal plane (e.g., byaltering corresponding features across the sagittal plane, for example,by altering anterior features relative to corresponding posteriorfeatures). Alignment deformities in both the coronal and sagittalplanes, or in multiple planes about the mechanical axes, can beaddressed by designing and/or selecting one or more resectiondimensions, one or more implant component thicknesses, and/or one ormore implant component surface curvatures.

In certain embodiments, an implant component that is preoperativelydesigned and/or selected to correct a patient's alignment also can bedesigned or selected to include additional patient-specific orpatient-engineered features. For example, the bone-facing surface of animplant or implant component can be designed and/or selected tosubstantially negatively-match the resected bone surface. If resectiondimensions are angled, for example, in the coronal plane and/or in thesagittal plane, various features of the implant component, for example,the component bone-facing surface, can be designed and/or selected basedon an angled orientation into the joint rather than on a perpendicularorientation. For example, the perimeter of the tibial implant or implantcomponent that substantially positively-matches the perimeter of thepatient's cut tibial bone has a different shape depending on the angleof the cut. Similarly, with a femoral implant component, the depth orangle of the distal condyle resection on the medial and/or lateralcondyle can be designed and/or selected to correct a patient alignmentdeformity. However, in so doing, one or more of the implant or implantcomponent condyle width, length, curvature, and angle of impact againstthe tibia can be altered. Accordingly in certain embodiments, one ormore implant or implant component features, such as implant perimeter,condyle length, condyle width, curvature, and angle is designed and/orselected relative to a sloping and/or non-coplanar resection cut.

FIG. 14 depicts a back view of a tibial guide box. The back view shows awidth 340 of the slot and a height 330 of the slot. The width of theguided slot 340 may also be specifically designed to control the widthof the cut as required by the surgeon—it may be wider, it may be shorteror a specific cut shape. In various embodiments, the width of thepreferred embodiment could substantially match the width of the specificimplant components that will be placed on the tibia. The height 330 ofthe guided slot will desirably determine the cut depth of the tibialplateau, with the angulation of the slot similarly controlling and/orinfluencing the angulation of the cut plane (in both medial/lateralangulation as well as anterior/posterior angulation). In variousembodiments, the cut plane height and/or angulation(s) may be patientspecific as determined by each patient's anatomy, or some or all cutplane features could be “dialed in” using an adjustable mechanism asseen in FIG. 13B.

FIG. 15 depicts a side view of a tibial guide box. The side viewhighlights the detent 350 which can used in various embodiments to lockinto the detent receiver holes 230 (see FIG. 5). One or more of thesedetents can be placed on opposing sides of the box to ensure that anaudible sound is heard (or other indication is provided) when lockingthe tibial guide box into the tibial guide housing.

FIGS. 16A-16C depict an isometric view, a front view, and a back view ofthe tibial guide assembly, respectively. These shaded views show how anexemplary tibial guide box can fit within a corresponding tibial guidehousing.

Improved Methods of Using a Tibial Guide Assembly

One preferred embodiment of the various teachings herein includesproviding an apparatus and method for preparing the tibia for a tibialimplant that significantly reduces the number of parts and componenttools required to resect and prepare a tibial plateau, and desirablyreduces the number of steps typically required in such a procedure. Oneof the many advantages of various embodiments described herein is thatthe assembly and associated components are modular, which allows thetibial housing to remain attached on the tibia, while multiple tibialguide boxes with varying cut depth dimensions, varus/valgus angles, andposterior/anterior cut angles can be utilized by the surgeon to makeadditional cuts and/or increase or modify the depth of cuts.

FIG. 17A depicts a top view of an uncut patient tibia 400 that has beenmodeled using a computer system. In this embodiment, there are threepotential planes that the surgeon will be considering, which are themedial 370, the center 380 and the lateral 390 planes. Each of theseplanes has varying bone morphology that is shown by the articular ridges360, and each plane may require a tibial guide assembly that attaches tothe bone using the natural conforming bone anatomy adjacent thereto. Thenatural placement and positioning of an implant using the naturalconforming bone anatomy will desirably provide the surgeon with a moresecure tool to prepare and cut the tibial plateau.

FIG. 17B shows an anterior view of a patient's uncut tibia and themedial and lateral intercondylar tubercle 410. This figure highlightsthe complex anatomy of a tibia and the varying exemplary cut planes 420that a surgeon may desire in creating one or more desired cut planes toaccept a tibial implant. The varying cut planes 420 show that thesurgeon has already predetermined the cut depth, the varus/valgus angle,and the posterior/anterior angles that he or she wishes to make toprepare the tibia. However, once the surgeon has made one or moresurgical access incisions and is able to directly visualize and/orobserve the knee anatomy and the preparation required to cut the knee,the surgeon has the flexibility to adjust the predetermined cuts byusing varying modular guide cut boxes with different cut depths and/orangles. For example, in one embodiment, if the surgeon wishes to cutless bone than originally predetermined, then the surgeon may choose the“Minus 2” tibial guide box instead of the “zero” guide box. This willallow the surgeon to cut less bone than what was originallypredetermined.

FIG. 18 depicts an anterior view of a tibial guide housing 25 positionedon the medial side of the tibia 400 and showing the reference arms witha patient specific contact surface 90 conforming to the natural anatomyof the bone; the resection guide is aligned primarily to match naturallandmarks of the articular surface or other features of the tibialplateau. Once a desired natural conforming position is found, thesurgeon may score the articular surface to reach the subchondral bone toensure proper positioning and placement, if desired. After the positionhas been determined, the surgeon may choose to determine the patient'smechanical axis with reference to their anatomical axis with analignment rod or equivalent systems. For example, an alignment rod maybe attached to a tibia guide housing 170 as shown in FIG. 19 and canextend to the patient's ankle to be parallel to the tibia's mechanicalaxis. The alignment rod system may be designed to be telescoped betweenits two connection points, which assists with the alignment of thepatient's mechanical axis and provides preferred positioning that may beadjustable. The use of the alignment rod may, in various embodiments,provide the surgeon with an additional confirmation that the housing 170is aligned with the correct patient-specific anatomy.

Once the alignment system is positioned, the tibial guide housing may beattached to the tibia using known methods and tools available in the OR,or provided in an instrument kit; and such attachment may includesecurement using a pin arrangement, e.g., by fitting one or more pinsthrough appropriate openings in the tibial guide box (see FIG. 6) and/orthe tibial guide housing. In various embodiments, after attaching thetibial guide housing to the anterior surface of the bone, apredetermined or adjusted tibial guide box may be inserted into thetibial guide housing. A reciprocating saw or similar cutting device canbe fitted through a cutting guide slot in the tibial guide box andreciprocated or otherwise manipulated or employed to cut across themedial side 450 (see FIG. 20) tibial plateau with a predetermined oradjusted cutting plane 430. If the surgeon is satisfied with the cut,the entire tibial guide assembly may be removed and, if desired, theguide pins may be left in place and the steps may be repeated for thelateral side of the tibia using another lateral side tibial guideassembly. FIG. 20 depicts the top view of the tibial guide assembly andexemplary medial 450 and lateral 460 cut planes.

FIG. 22 depicts a side view of a tibial guide assembly after both medial450 and lateral 460 sides of the tibia have been resected; this figurehighlights the uniformity of the entire cut tibial surface 460 whenusing the tibial guide assembly and captured/guided cut boxes. Invarious alternative embodiments, the medial and lateral cut planes maynot be parallel, offset, and/or coplanar. At this time, the surgeon canremove the tibial guide assembly leaving the positioning pins for boththe medial and lateral cuts in place to conduct a trialing and fixationof the knee prosthesis. The trialing may involve fitting the prosthesiscomponents to the prepared surfaces and checking the patient's range ofmotion, alignment, and the ligament stability that will approximate therange of motion of a natural knee. In at least one exemplary embodiment,the proximal tibial end can preferably be first fitted with a variety oftemplates and measuring tools and be followed by fitting the femurportion of the prosthesis to the prepared distal femur end.

If various trialing steps do not optimally fit the trial implantprosthesis, additional cuts on the tibia may be made. For example, ifthe knee is tight in extension and flexion, the tibia may be furtherresected as necessary using the tibial guide assembly and adjusting thetibial guide boxes 480 (in FIG. 23) to preferred cut depth and angles.If the knee is tight in extension and balanced in flexion, the distalfemur may be cut. Lastly, if the knee is tight in flexion and balancedin extension, it is possible that the surgeon may choose a tibial guidecut box to add posterior/anterior slope to the already cut tibialsurface. However, many other combinations may be found to optimallyadjust the cut depth 470 of the tibia resected surface using the guideboxes and combinations of guide boxes with varying dimensions or angles.

Once the proper alignment and balancing of the trial implants have beenperformed, the surgeon may secure the actual knee joint components andpatella prosthesis to the patella. The result can be tested andthereafter the incision into the knee can be appropriately closed anddressed.

What is claimed is:
 1. A tibial guide housing for use in treatment of atibia of a patient, the tibia having a tibial plateau, the tibial guidehousing comprising: a top side generally opposite a bottom side and afront side generally opposite a back side; a first reference arm havinga patient-specific contact surface configured to conform to a firstportion of a superior surface of the tibia; a second reference armhaving a patient-specific contact surface configured to conform to asecond portion of the superior surface of the tibia; and at least onepin hole configured to accommodate insertion of a pin through the tibialguide housing and into the tibia, wherein the back side includes apatient-specific contact surface configured to conform to a portion ofan anterior surface of the tibia.
 2. The tibial guide housing of claim1, further comprising a third reference arm having a patient-specificcontact surface configured to conform to a third portion of the superiorsurface of the tibia.
 3. The tibial guide housing of claim 1, whereinthe patient-specific contact surface of each reference arm is configuredto engage an articular surface of the tibial.
 4. The tibial guidehousing of claim 1, wherein the patient-specific contact surface of eachreference arm is configured to engage subchondral bone surface.
 5. Thetibial guide housing of claim 1, wherein the top side includes apatient-specific alignment indicator configured to provide visualassistance for alignment of the tibial guide housing with respect to thetibia.
 6. The tibial guide housing of claim 5, wherein the alignmentindicator comprises one or more channels formed in the top surface ofthe tibial guide housing.
 7. The tibial guide housing of claim 5,wherein the alignment indicator is positioned and shaped based, at leastin part, on patient-specific information to substantially match aportion of a perimeter of the tibia when the tibial guide housing ispositioned on the tibia in a predetermined alignment.
 8. The tibialguide housing of claim 1, further comprising an alignment leg, thealignment leg configured for attachment to a tibial alignment rod. 9.The tibial guide housing of claim 1, further comprising a viewing windowconfigured to permit viewing of a peripheral edge of a portion of theanterior surface of the tibia from the top side of the tibial guidehousing during positioning of the tibial guide housing on the tibia.